We are continuing to study the immunosuppressive effects of serum drawn from cancer patients with particular attention to a series of sera from patients with malignant melanoma. Having already determined that suppression of PHA induced blastogenesis of normal human lymphocytes is dependent upon the presence of a specific subpopulation of lymphocytes, we will continue to manipulate cell populations to determine the mechanism of their influence on antigen response in the presence of immunosuppressive serum. In addition, we hope to begin to identify the location of serum activity by 2-dimensional electroimmuno-diffusion, and manipulate specific serum proteins to determine immunosuppressive mode of action. We intend to begin study of the effects of in vivo administration of immunosuppressive serum to animals to help determine mode of action and range of effect. BIBLIOGRAPHIC REFERENCES: Ninnemann, J.L., and J.C. Fisher, 1977. "Immunosuppressive Proteins in the Serum of Breast Cancer Patients." Federation Proceedings 36:1270. Ninnemann, J.L., 1977. "Identification of Breast Cancer Associated Immunosuppressive Serum Proteins by Crossed Immunoelectrophoresis." Cancer Research (Abstract) (in press).